At 1:12 PM -0400 10/25/2010, John Martz wrote:
On Thu, Oct 21, 2010 at 2:16 PM, JoeTaxpayer wrote:
> I never say never, but I've been watching this industry for nearly 30
years, and suspect that until and unless SSD cost drops to a lower X
of HD, both will be there side by side depending on the platform it
goes in.
If you're going to discuss SSDs versus HDs then I suggest you also
consider the relatively recent availability of hybrid SSD-HDs.
Yea. sigh. IMO, a stupid stupid idea.
It is akin to partial-hybrid cars, you know, the gas-powered ones
with electric assist that get lower gas mileage than many of today's
modern all-gas cars. A stop gap for the industry to market to
unsuspecting consumers, while they screw around instead of just
putting out real hybrids (electric cars with gas assist) in the first
place.
At the moment the only one I know of is Seagate's Momentus XT which I
understand to be a 7200 RPM 2.5" drive with the traditional 32MB RAM
cache but also a 4GB SSD. The pertinent difference here is probably
not so much the 4GB of SSD but whatever "dynamic caching" algorithms
Seagate has come up with. (I'm just guessing of course).
Let's think about this.
Instead of
interface <-> cache <-> HD,
you now have
interface <-> cache <-> big flash cache organized as a SSD <-> HD.
Think about that. The firmware and hardware controllers, to drive
the simpler design, have been in the field for years and are
thoroughly debugged. So now they're adding a massive layer of
complexity... How many firmware updates will there be? And how will
your data suffer until they're released? Oh wait - most of these
devices don't have user updatable firmware!
Oh, but the performance of SSD! yea. heh. If this is a laptop
form factor, then you still have the power sucking HD behind things.
If this is a desktop then what exactly will it do for you that a RAM
Disk couldn't do better? What happens when things gak before the
write-through to the SSD then to the HD is completed?
And then there's the problem of the life span of the flash memory
(thousands of writes, not millions). Yea. Let's take a
high-quality data retention and high re-write life device, and strap
a lower-quality brick to its forehead. Sure the brick is faster.
But it's still a brick.
heh.
- Dan.
--
- Psychoceramic Emeritus; South Jersey, USA, Earth.
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